50 MR. F. E, BEDDARD ON THE ANATOMY [Jan, 15, 



(3) The Position of the Umbilicus in certain Vipers. 



I am not aware that the point of entrance of the umbilical sac 

 into the body in Snakes has ever been made use of as a systematic 

 character. I find, however, from a few observations that I have 

 been able to make recently, that this anatomical relationship is 

 apparently of systematic value. Since of one species, viz. Lachesis 

 lanceolatus, selected for these observations, I have been able to 

 examine a considerable number of individuals, the variation of 

 the character from one individual to another became a matter of 

 additional interest, especially in view of the fact that all the indi- 

 viduals were of one brood. It appears that in Vipei'S, as compared 

 at any rate with the Anaconda*, the umbilicus is much nearer tothe 

 cloacal aperture. I have examined fourteen individuals of Lachesis 

 lanceolatus of the same brood and of approximately the same size, 

 though they died on different dates, from March the 9th to May. 

 The length varied from llg to 12 inches exclusive of the short 

 tail. I do not give measurements in millimetres, since to use such 

 gives an appearance of rigid accuracy not attainable in a dead 

 snake capable of artificial extension and shortening. In nearly 

 all of these fourteen individuals four scales occupied the umbilical 

 region, each of them being bisected by a groove running longi- 

 tudinally to the axis of the body. I found, in fact, that there 

 were four scales thus modified in eleven individuals. In two of 

 the remaining snakes thei-e were five of these scales in which the 

 two sides had not joined across the middle ventral line, and in 

 the fourteenth individual only three scales and a portion of the 

 fovirth ; the number of scales intervening between the last of the 

 " umbilical " scales and the anal scale varied a good deal but within 

 very narrow limits. The actual facts are these : in three speci- 

 mens 17 scales intervened between the points mentioned ; in one 

 specimen 18 scales; in five othei-s 19 scales; in three 20 scales; 

 in one 21 scales ; and, finally, in one 22 scales. The average is 

 thus arithmetically 19, and actually there were more specimens 

 exhibiting the average than any other number. Having due 

 regard to the narrow range of the variation, it seems likely that 

 the position of the umbilicus in this species of Yiper can be 

 regarded with safety as lying 19 scales in front of the anal scale. 

 It is important to notice the length of time during which this 

 foetal character is retained. The last specimens examined by 

 myself died on May 15th of last year. These and the other 

 individuals were acquired by the Society on Dec. 12th, 1905. 

 The last specimens examined by me were therefoi'e more than six 

 months old. I have some confidence, therefore, in comparing 

 Lachesis lanceolatus in respect of these chai'acters with other 

 Vipers of an obviously greater age. I may first of all, however, 

 refer to newly-born Vipers which I have i-ecently dealt with t in 



* See Beddavd, P. Z. S. 1906, vol. i. p. 13. 

 t r. Z. S. 1906, vol. i. p. 34. 



